fix: optimize BigInt usage in hash function

[reallesee]

Description

Replace BigInt(8) with 8n literal in bit shift operation to improve performance by avoiding unnecessary BigInt object creation.

Checklist

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I have run yarn format and yarn lint without getting any errors
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[vplasencia]

Looks great! Thank you very much @reallesee

[gitpoap-bot]

Congrats, your important contribution to this open-source project has earned you a GitPOAP!

GitPOAP: 2025 Semaphore Contributor:

Head to gitpoap.io & connect your GitHub account to mint!

Learn more about GitPOAPs here.